In its simplest form, an aircraft may be guided along a taxi path by a crew member manually steering the aircraft using a flight deck controller (e.g. a tiller) while looking out a window. In this case, the crew member utilizes their best judgment regarding how to guide the aircraft along an acceptable taxi path. Various visual guidance systems have been utilized to improve upon manual steering. Visual guidance systems generally determine a taxi path based on supplied inputs such as air traffic control (ATC) clearance, and present instructions for guiding the aircraft along the suggested taxi path; e.g. speed, steering, when to turn thrust engines off and when to turn electric drive motors on, etc. ATC clearance input can include taxi route, assigned take-off or landing runway, hold points, etc.
An aircraft may be powered during the taxi by a traditional taxi system or by an electric taxi system (ETS). Traditional aircraft taxi systems utilize the primary thrust engines (running at idle speed) and the braking system of the aircraft to regulate the speed of the aircraft during taxi. The electric taxi system (ETS) is an efficient upgrade to the traditional taxi system for aircraft. Electric taxi systems have traction drive systems that employ electric motors that can be powered by an auxiliary power unit (APU), rather than the primary thrust engines. Aircraft equipped with ETS have the ability to autonomously push back from the terminal, and are therefore not reliant upon the conventionally used pushback tractors, or tugs. Further, the ETS can provide most of the basic functions of tugs, and can serve as the main engine for taxiing
The ETS also provides expanded turning capability. Traditional steering is performed by the aircraft nose wheel, and the radius of turn achieved is affected by aircraft size and wing length (generally approximately 60 degrees). In contrast, the ETS can control the main landing gear (MLG) relative speed between left and right wheels, resulting in sharper turns than what can be achieved by traditional steering (approximately 60-90 degrees). The ETS supported turns are referred to as “tight turns” or tight turn operations. All of the aforementioned advantages provided by ETS are autonomous.
During various aircraft ground operations such as a taxi, a tight turn, or a reverse operation, a deviation from an airport active surface area may occur. Traditionally, tools such as moving maps on Heads Down Displays, Heads Up Displays, Surface Guidance Systems, Enhanced Vision Systems, and the like, have been utilized to minimize the likelihood of occurrence of such a deviation. However, what is lacking is a tool to display an alert, such as an audible alert, a warning text, or a graphical representation of corrective action, when a deviation from the airport active surface area is predicted.
Accordingly, an aircraft taxi path guidance and display system that graphically displays an alert and corrective action when a deviation from the airport active surface area is predicted is desirable. It is desirable for the system to also display the alerts and corrective action for tight turn and reverse operations. Such an aircraft taxi path guidance and display system would increase situational awareness by proactively alerting the crew to avert predicted deviations.
Other desirable features will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.